This invention relates to large multi-unit steam generating systems, and in particular to systems in which one steam generating unit in the system is supplied with an intermittently heated flow of a molten salt heat transfer medium.
In recent years attention has been focusing on the use of renewable energy resources as a way of providing high quality energy, such as electricity or process steam from central generating stations. One such system is a co-generating power plant having a conventional fossil fuel unit partially repowered by a solar central receiver unit. Typically, molten salt is considered the ideal heat transfer medium for the solar unit.
Inherently, a molten salt solar receiving and steam generating unit is intermittent in operation. This type of unit requires a supplemental supply of thermal energy capable of maintaining undrained system components above the melting point of salt during inactive periods to avoid material degradation resulting from thermal cycling. Traditionally, a similar requirement in liquid metal systems has been fulfilled by the use of electrical trace heating. Conventional thinking for molten salt units appears to be following this precedent.